Four-component symmetrical projection objective



SR SEARCH m QR 39 vr T I 1968 R. A. BUCHROEDER ET AL 3,418,033

FOUR-COMPONENT SYMMETRICAL PROJECTION OBJECTIVE Filed April 20. 1966RICHARD A. BUCHROEDER GEORGE E ZIEGLER INVENTORS ATTORNEY United StatesPatent "ice The present invention relates to optical'objectives and moreparticularly it relates to improvements in projection objectives of thesymmetrical type.

Objectives of this kind are represented in the prior art by the patentto Rudolph, German Patent No. 310,615, issued Mar. 15, 1918, and areintended to be used for copy work at unity magnification.

An object of the present invention is to provide a novel copyingobjective of symmetrical form having a relative aperture at least aslarge as f/5.6 at infinity, a total conjugate length of substantially23.5 inches, said objective being corrected for all ordinary chromaticand monochromatic image aberrations including curvature of field anddistortion.

Further objects and advantages will be apparent in the details describedin the following specification taken together with the accompanyingdrawing wherein the single 2 figure is an optical diagram showing apreferred form of the present invention.

The objective is generally designated by the numeral 10, and consists ofa front and a rear group of lenses constituting the aforesaid objective,the two duplicate groups confronting each other on either side of aninterposed air spaced diaphragm 11 and being mutually aligned on acommon axis 12. Each said group consists of a doublet lens member ofmeniscus form which is duplicated in the other group and is concavetoward the diaphragm 11. Said I doublet front and rear lens members arenumbered 13 and 14 respectively and are each composed of an outerconvex-concavo lens element designated I which is cemented along aninterface to an inner convex-concavo lens element designated II. 7

Between the doublets 13 and 14 are spaced a pair of duplicate singletmeniscus lens members which are both designated III, these singletsbeing arranged concave toward said interposed diaphragm 11 as shown inthe draw- Both groups of lens members I to III 'are symmetricallyarranged between an object plane 15 and an image plane 16 whereat theobjective forms an image at unity magnification, the front and rear airspaces being designated 8; and S respectively and being substantiallyequal in value. The air space between doublet lens member 13 and singletlens member III is designated S and the corresponding air space betweendoublet 14 and the adjacent singlet III is designated S like the frontgroup of lenses. Duplicate air spaces 8;, are provided at either side ofdiaphragm 11 between the singlet lenses III.

3,418,038 Patented Dec. 24, 1968 The successive lens elements I to IIIon each side of the diaphragm 11 have their axial thicknesses designatedt to t; respectively numbering toward the diaphragm andthe successivelens surfaces of said elements are designated R to R for the front groupand -R to R,, for the rear group, the minus sign used with. certain Rdesignations meaning that such surfaces are concave toward the objectsurface 15. Therefore, all of the lens surfaces are concave toward thediaphragm.

According to the present invention, the lens parameters, such as focallengths, lens surface radii, lens thicknesses and refractive index ofthe glass from which each lens element is made, are so chosen bycomputation and experiment that all of the aforesaid objects andadvantages are achieved. In the table herebelow are given substantiallythe values of the above-mentioned lens parameters in terms of F which isthe equivalent focal length of. the objective 10 although it should beunderstood that slight variations of such values within manufacturingtolerances are allowable. The successive focal lengths in the table aredesignated F -F F for each lens group relating to .lens elements I, Hand III respectively thereof, Furthermore, the following table gives thevalues substantially in terms of F for the lens thicknesses t to t lensradii R to R and air spaces S to S Additionally, the values forrefractive index n (I) to n (III) and for Abbe numbers v(I) to v(III)related to the optical materials of the lens elements I to III are givenin said table.

Table of values n (II)=1.605 n (III)=l.638

wherein F represents the equivalent focal length of the objective 10.

More specifically, the constructional data related to the objective 10is given numerically in the tabulation herebelow wherein all scalarquantities are given in millimeters and wherein the symbolism remainsthe same as hereabove E.F.L.=148. 58 B.F.L.=129.58 f/5.6

Lens Focal Length Radli Thick- Spaces m) w nesses I and II (Doublet)..Fm=1214.03

\ S =278.16 R and --Ri=35.98

I Fr=59.99 t1=7.81 1. 670 47. 2

v R: and R:=313.33 II --Fn=49.50 ta=4.l1 1. 605 38.0

R: and Ra=27.20 v

Sl=3.19 R4 and R4=39.50 III F|u=177.78 l:=3.14 1.638 55.5

R; and Rs=58.73

Sa=2.65 S =278.16

3 4 Although only one form-of the present invention has been Table ofvaluesCntinued shown and described in detail, the values of the paramt.0526F eters given are nominal or ideal in character and small tvariations from the nominal values may be tolerated with- 0215: outsignificantly detracting from the performance quality 5 s ig' 87Fthereof within good manufacturing practice. 5

We claim:

S .0178F 1. A symmetrical Pl'OjCCtlOn ob ective for use at equal n (I)-1.670 con ugates having an aperture of substantlally f/5.6, said n (H)1 605 objective comprising n 638 a pair of negative meniscus doubletlens members which (I) are duplicates of each other and are concavetoward I v(II) 38.0 each other, said members being equally spaced fromu(III) 55 5 opposite sides of an interposed diaphragm and beingoptically aligned on a common axis, each of said wherein F representsthe equivalent focal length of members being composed of an outerconvex-concave the obieclivelens element of positive power designated Iwhich lies A symmeffical p l Q oblectlve f use at equfll in contact withan inner co vexo negative con ugates having an aperture of substantiallyf/5.6, said lens element designated II, said objective being furtherobiectlye P composed of a pair of singlet positive meniscus lens a palrof negative meniscus doublet lens members WhlCh members designated IIIspaced between said doublet are duplicates each Other are Concave towardmembers and spaced symmetrically from either side each other, saidmembers being equally spaced from of said diaphragm and being concavethereto, said opposite sides of an interposed diaphragm and beingmembers and elements having lens parameter values op i lly allflned On aCommon 3X15, each of 531d as specified in the table herebelow wherein F-F 5 members being composed of an outenconvex-concavo and F designatethe focal lengths of th l ses I, lens element of posltive powerdesignated I WhlCh II and III respectively and the minus sign means liesin contact with an inner convex-concave negative negative focal length,R to R and R to -R lens element designated II, said objective beingrepresent the radii of the successive lens surfaces and further composedof a pair of singlet positive the minus sign used therewith means thatsuch mefllscl15 16115 members designated 1H Spaced radii are concavetoward the obect side, t to t repretween said doublet members and spacedsymmetrisent the successive axial thicknesses of said lenses c lly omelther side of said diaphragm and being numbering toward the diaphragm,S and S represent concave thereto, said members and elements having thefront and back air spaces, 8; represents the space lens parameter numercal values as specified in the between the doublet lens and the singletlens, 8 reprelable herebelow wherein r, n and m deslgnate sents the airspaces at either side of the diaphragm, the focal lengths of the lensesI, II and III respecand u and 11 represent the refractive index and'Abbelv ly and the minus g means negatlve 0 3! number respectively of theglasses from which the length, R; to R and R to R represent the radiilenses are made, of the successive lens surfaces and the minus 40 signused therewith means that such radii are con- Table of values cavetoward the object side, t to t represent the r=- successive axialthicknesses of said lenses numbering F =.333F toward the diaphragm, Sand S represent the front F =l.194F and back air spaces, 8;; representsthe space between R ='R =.242F the doublet lens and the singlet lens, 8;represents R =-R =2.l05F the air spaces at either side of the diaphragm,and R =-R =.183F n and 11 represent the refractive index and Abbe R =R-=.266F number respectively of the glasses from which the R R =.395Flenses are made,

E.F.L.=148.58 B.F.L.=129.58 f/5.6

Lens Focal Length Radii Thick- Spaces 1m w I and II (Doublet)..Fm=1214.03

. s,=27s.1e R and -R =35.98 I Fr=59.99 t1=7.s1 1.670 47.2

R1 and R2=313-33 II Fr =49.50 tr=4.11 1.605 33.0 R2 and -Ra=27.20

* Sz=3.19 R and R4=39.50 III Fm=177.78 n=3.14 1.638 55.5

R; and R =58.73

S3=2.65 Sl=278.16

References Cited -UNITED STATES PATENTS 2,601,595 6/1952 Cook.

3,221,601 12/ 1965 Betensky et a1.

US. or, X.R.

'5 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,418,038 December 24 1968 Richard A. Buchroeder et a1.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as show below:

Columns 1 and 2, in the table, second column, line 1 and columns 3 and4, in the table, second column, line 1 thereof, "F 1214.03", eachoccurrence, should read F 1214.03 Column 2, line 50,

"\)(II) 55.5" should read \J(III) 55.5

Signed and sealed this 17th day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

1. A SYMMETRICAL PROJECTION OBJECTIVE FOR USE AT EQUAL CONJUGATES HAVINGAN APERTURE OF SUBSTANTIALLY F/5.6, SAID OBJECTIVE COMPRISING A PAIR OFNEGATIVE MENISCUS LENS MEMBERS WHICH ARE DUPLICATES OF EACH OTHER ANDARE CONCAVE TOWARD EACH OTHER, SAID MEMBERS BEING EQUALLY SPACED FROMOPPOSITE SIDES OF AN INTERPOSED DIAPHRAGM AND BEING OPTICALLY ALIGNED ONA COMMON AXIS, EACH OF SAID MEMBERS BEING COMPOSED OF AN OUTERCONVEX-CONCAVO LENS ELEMENT OF POSITIVE POWER DESIGNATED I WHICH LIES INCONTACT WITH AN INNER CONVEX-CONCAVO NEGATIVE LENS ELEMENT DESIGNATEDII, SAID OBJECTIVE BEING FURTHER COMPOSED OF A PAIR OF SINGLET POSITIVEMENISCUS LENS MEMBERS DESIGNATAED III SPACED BETWEEN SAID DOUBLETMEMBERS AND SPACED SYMMETRICALLY FROM EITHER SIDE OF SAID DIAPHRAGM ANDBEING CONCAVE THERETO, SAID MEMBERS AND ELEMENTS HAVING LENS PARAMETERVALUES AS SPECIFIED IN THE TABLE HEREBELOW WHEREIN FI, -FII AND FIIIDESIGNATE THE FOCAL LENGTHS OF THE LENSES I, II AND III RESPECTIVELY ANDTHE MINUS (-) SIGN MEANS NEGATIVE FOCAL LENGTH, RI, TO RK AND -RI TO -R5REPRESENTS THE RADII OF THE SUCCESSIVE LENS SURFACE AND THE MINUS (-)SIGN USED THEREWITH MEANS THAT SUCH RADII ARE CONCAVE TOWARD THE OBJECTSIDE, TI TO T3 REPRESENT THE SUCCESSIVE AXIAL THICKNESSES OF SAID LENSESNUMBERING TOWARD THE DIAPHRAGM, SI, AND S4 REPRESENT THE FRONT AND BACKAIR SPACES, S2 REPRESENTS THE SPACE BETWEEN THE DOUBLET LENS AND THESINGLET LENS, S3 REPRESENTS THE AIR SPACES AT EITHER SIDE OF THEDIAPHRAGM, AND ND AND V REPRESENT THE REFRACTIVE INDEX AND ABBE